Period confusion 😭

Had normal period for the last 2 days (heavy cramping, blood clots, cranberry red) I use a menstrual cup and had to dump it at normal times. Then I got up this morning, took out my cup and there was seriously little to no blood in it! Went to the gym this morning, had no cramps until the very end and when I got home the cramps were because of another big clot but after that it’s been back to slim to non. It’s still red but there’s just such a small amount! I’ve been under a lot of stress due to the fact that I’m leaving the country in a month by myself and I now go to the gym 5 times a week and have been really stepping it up there (I’ve only been going a little over a month). Is that why my period is cut short? I took a pregnancy test today because I was freaking out so badly.... it was negative. am I sick?? I’m just so confused, my period is normal 4-5 days....